Animal with lengthened rostrum ; tentacles subulate, with the eyes at their outer bases ; mantle-margin fringed ; foot suborbicular, simple ; gill-plume placed obliquely across the mantle-cavity, the elongate linear laminae partly exposed. Central tooth of the radula trapezoidal, the reflected margin triangular, having long sharp median and very fine lateral cusps; laterals multicuspidate; marginals simple.
Shell conical, provided with epidermis, apex posterior and directed to the right, more or less spirally curved ; aperture basal, the lip continuous, no inner process, the horseshoe-shaped muscular impression on the inner wall.
The few species inhabit the seas of Europe, the East and West Indies, western America, Australasia.
Fossil.—The genus commenced with the Silurian.